A vehicle comprising one steerable axis, e.g. in the form of a steerable axle connected to two wheels of the vehicle, and one fixed axis, e.g. in the form of an axle connected to two other wheels of the vehicle, is normally controlled by the operator of the vehicle steering the steerable axis by means of a steering wheel.
In a vehicle comprising two steerable axes and one fixed axis the steering wheel will normally be used for steering the two steerable axes in accordance with a specific relationship between the two steerable axes. The specific relationship between the two steerable axes is given by the relative position of the three axes of the vehicle.
In a vehicle comprising two steerable axes and no fixed axis, the two steerable axes are also steered by means of a single steering input from a steering wheel. In this case the operator of the vehicle will typically be able to choose between a number of different steering modes, which define how the two steerable axes are to be steered relative to each other. The available steering modes could, e.g., include front steering mode, rear steering mode, centre steering mode and/or dog steering mode.
Thus, in prior art control methods a fixed steering mode must be selected among the available steering modes, and once a fixed steering mode is selected, the steerable axes of the vehicle are controlled by means of a steering input from a steering wheel, according to a mutual relationship which is determined by the selected steering mode.